不同防风措施对赤皮青冈容器苗的抗风效果     

殷芳芳  林夏珍  胡丽鹏  宁梦雅 《林业科技开发》2014,28(2)

在模拟自然风的情况下,对4年生赤皮青冈容器苗在无任何抗风措施、搭支架、半埋入地下、半埋入地下兼搭支架、半埋入地下兼连体绑扎等处理下的形态特征变化、风害情况以及抗风指数进行了研究和分析.结果表明采取半埋入地下兼连体绑扎措施时4年生赤皮青冈容器苗受到的风害最小,抗风等级最高,其次分别为丰埋入地下兼搭支架、半埋入地下、搭支架和无任何抗风措施.因此建议沿海地区进行赤皮青冈容器苗生产时,可采取半埋入地下兼连体绑扎措施来防御台风.  相似文献   

蚕沙对14～70日龄仔鹅生长性能、体尺性状、屠宰性能和脏器指数的影响   总被引：1，自引：0，他引：1  

张得才  王志跃  杨海明  巨晓军  谢燕娟 《动物营养学报》2014,(12):3772-3780

本试验旨在研究饲粮中添加不同水平蚕沙对14~70日龄仔鹅生长性能、体尺性状、屠宰性能和脏器指数的影响,以确定仔鹅饲粮中蚕沙的适宜添加水平。选取330只11日龄健康、体重相近的扬州鹅公鹅,随机分为5个组,每组6个重复,每个重复11只鹅。对照组饲喂基础饲粮,试验组分别饲喂添加3%、6%、9%、12%蚕沙的试验饲粮。试验期56 d。结果表明:1)与其他试验组相比,饲粮中添加9%和12%蚕沙显著降低了28、35、42、49、56、63和70日龄仔鹅体重(P<0.05),显著降低14~28日龄、29~70日龄和14~70日龄仔鹅平均日增重(P<0.05),显著提高了料重比(P<0.05)。2)与对照组相比,饲粮中添加9%和12%蚕沙显著降低了胫围、胸宽、胸深、体斜长和半潜水长(P<0.05)。3)饲粮添加蚕沙仅对仔鹅胸肌率有显著影响(P<0.05)。4)饲粮添加蚕沙显著影响了仔鹅十二指肠指数、空肠指数、回肠指数、盲肠指数和直肠指数(P<0.05)。由此可知,饲粮添加3%~6%蚕沙对仔鹅生长性能、体尺性状、屠宰性能、脏器指数没有不良影响,且对肠道的生长发育有一定的促进作用。在生产实践中仔鹅饲粮中蚕沙的添加水平不宜超过6%。  相似文献   

Issues and pitfalls in method comparison studies     

Sonja Hartnack 《Veterinary anaesthesia and analgesia》2014,41(3):227-232

Method comparison studies are needed for validation of new methods of measurements, for example, non‐invasive blood pressure measurements against standard reference methods. After a brief introduction into method comparison studies, this paper is organized in three sections. The first section deals with the widely, though not always appropriately, used classical Bland‐Altman plot with the limits of agreement and its extensions with non‐constant bias and multiple observations. The second section comments on other statistical approaches including correlation coefficients, linear regressions and sensitivities and specificities which are sometimes seen in method comparison studies. The third section proposes the usage of linear mixed effects models as a flexible way to deal with questions associated with method comparison studies.  相似文献   

论甘肃林业人力资本与林业的可持续发展     

张肃斌 《甘肃农业大学学报》2006,41(2):119-123

实现林业的可持续发展,人力资本在生产力发展中的地位和作用显得越来越重要.通过对人力资本与林业可持续发展的理论关系及甘肃林业人力资本现状分析,提出合理开发甘肃林业人力资源与推进林业的可持续发展的对策,以期对甘肃林业的可持续发展提供参考.  相似文献   

A comparison of two methodologies for assessment of irrigation performance under the Warabandi system     

H. Goldsmith  I. W. Makin 《Irrigation and Drainage Systems》1991,5(1):19-29

A water management study of Warabandi in northwest India in 1983 developed a methodology for assessing the performance of large scale smallholder irrigation schemes by observing irrigated areas and carrying out random crop cutting. A study of Warabandi in 1988 took a shorter amount of time and concentrated on direct measurements of flow and seepage in order to assess the performance of the physical conveyance system. This paper contrasts these two approaches and gives practical guidance on how to go about carrying out a rapid assessment of the performance of the physical conveyance system of an irrigation scheme.  相似文献   

溪洛渡水电站导流洞边墙衬砌混凝     

吴家冠  段亚辉 《中国农村水利水电》2007,(9):96-99

为探明导流洞边墙衬砌混凝土出现裂缝的原因，研究进一步采取综合温控措施防裂的有效性和合理性，采用三维有限元法模拟施工过程与温控措施进行仿真计算，用等效热传导方程，将水管冷却的降温作用视为混凝土的吸热，按负水化热处理，在平均意义上考虑水管的冷却效果。通过多方案的综合分析研究，分析边墙衬砌混凝土开浇后开始通水冷却通水时间的长短对水管冷却的效果。根据特定断面的表面点在不同时间的温度应力值，进一步了解溪洛渡导流隧洞边墙衬砌混凝土这一特定工程的温度应力情况，以提供今后隧洞工程衬砌混凝土施工参考采用。因此，对于隧洞衬砌结构施工期的前期温变效应进行仿真分析有着重大的工程意义。  相似文献   

联合收割机脱粒滚筒焊接质量在线检测系统     

苑严伟  方宪法  荣耀  樊红星  董鑫  李黎 《农业工程学报》2015,31(4):11-16

为解决联合收割机脱粒滚筒焊接过程缺乏有效检测手段导致质量差的问题,采用基于激光测距的焊接质量在线检测方法,开发脱粒滚筒焊接过程中滚筒圆柱度及外辐盘焊接垂直度在线检测系统,设计在线检测试验台,通过数据处理实现焊接质量的在线检测与变形报警。试验表明,滚筒圆柱度检测精度达0.059 mm,外辐盘焊接垂直度检测精度达0.023 mm,圆柱度检测最大相对误差为2.17%,垂直度的检测最大误差为1.93%,满足脱粒滚筒在线检测要求,检测效率提高到手工方法的20倍以上。系统的研制保证了大型联合收割机脱粒滚筒焊接质量,对提高联合收割机制造水平、保障作业可靠性有重要意义。  相似文献   

基于计算机视觉的水产动物视觉特征测量研究综述     

段延娥  李道亮  李振波  傅泽田 《农业工程学报》2015,31(15):1-11

作为水产养殖集成信息化管理的主要信息源,水产动物视觉属性信息的测量不仅是判定水产动物生长状况,调控水质环境的主要信息依据,也是对水产动物进行喂养、用药、捕获、选别和分级等操作的前提基础。近年来,计算机视觉技术作为一项快速、客观、无损的检测方法,已被逐渐用于水产动物视觉属性的测量中,许多研究学者开展了大量的研究工作。该文更新和总结了国内外近20多年来有代表性的相关研究和解决方案,在描述计算机视觉检测系统的概念和组成结构的基础上,围绕尺寸测量、形状分析、颜色识别和质量估计等方面详细分析了计算机视觉技术在水产动物(以鱼类为主)视觉属性测量方面的国内外研究现状,着重阐述总结了研究人员在水产动物视觉检测的图像采集、轮廓提取、特征标定与计算等方面的具体改进措施,并对基于计算机视觉测量的水产动物疾病诊断,识别分类等综合应用现状也进行了分析探讨,以评估计算机视觉技术在水产动物视觉质量检测领域的总体应用情况和现存的主要问题,同时给出了今后的研究趋势与发展方向。  相似文献   

Mensuration of the rabbit pituitary gland from computed tomography     

Vionna Kwan  Katherine Quesenberry  Alexandre B. Le Roux 《Veterinary radiology & ultrasound》2020,61(3):322-328

The aim of this retrospective reference interval observational study was to determine the mensuration of the pituitary gland (hypophysis cerebri) by analyzing CT studies in rabbits without clinical evidence of pituitary disease or central neurologic signs. Though diseases of the rabbit pituitary gland are uncommon, the pituitary gland is essential in regulation of the rabbit's endocrine system, as in other species. Currently, there are minimal published studies that detail the rabbit head anatomy on cross‐sectional imaging, and even less specifically examining the pituitary gland. The pituitary gland was measured by one observer at a single time point from transverse and reconstructed sagittal CT images in a soft‐tissue algorithm in 62 rabbits for a total of 66 rabbit head CT studies. The rabbits ranged from 0.84 to 14 years in age (mean ± SD: 5.46 ± 3.05 years) and 0.92 to 4.95 kg in weight (2.21 ± 0.83 kg). Linear pituitary measurements were performed using electronic calipers. The mean ± SD pituitary height was 4.22 ± 0.57 mm, width was 4.48 ± 0.71 mm, and length was 6.02 ± 0.70 mm. The pituitary gland height‐to‐brain area ratio was 1.10 ± 0.16 mm^?1, which is much higher than the values reported in normal dogs and cats. The age, weight, and sex of the rabbits were not found to have a significant impact on pituitary gland mensuration. These measurements could be useful as a reference range for future rabbit head CT studies and to rule out pituitary enlargement or disease when evaluating rabbit pituitary glands.  相似文献   

罗布泊"耳纹"成因与电磁感应电导仪测量值相关性初探     

谢云波  蒋平安  李保国  钟俊平  邱宏烈  武红旗  马黎春 《新疆农业大学学报》2007,30(2):30-32

应用EM38电磁感应电导仪测量法调查了罗布泊“耳纹”地区盐壳电导值，对干盐湖沉积物采取不同尺度和不同空间分辨率的取样与测量。研究结果表明，盐壳土壤EM38电导的各特征参数值均表现出明显的空间变异性，“耳纹”的形成和电磁感应电导所表征的物理量存在较好相关性：“耳纹”黑色区域电导值较高，白色区域电导值较低。  相似文献